1. Field of the Invention
This invention relates to a process for treating organic waste water by which to perform efficient treatment of organic waste water containing SS (suspended solids).
2. Description of the Prior Art
As a method of treating SS-containing organic waste water, there has been hitherto known a method in which, as shown in FIG. 1, an immersion type aerobic filter bed 100 packed with a granular filter medium is used.
In the figure, the immersion type aerobic filter bed 100 is packed with the filter medium 101. A diffuser pipe 102 for supplying air is disposed on the lower side of the filter medium 101.
Raw water, or waste water to be treated, is introduced into the immersion type filter bed 100 via an upper portion of the filter bed. While passing through the filter medium 101, the raw water is aerated by air supplied from the diffuser pipe 102, resulting in an aerobic treatment. Meanwhile, the SS are caught by the filter medium 101. The thus treated water is discharged to the exterior of the filter bed.
The immersion type aerobic filter bed method according to the prior art is extremely effective for the treatment of waste water which has a low SS content. For organic waste water having a high SS concentration such as raw sewage water, however, the conventional aerobic filter bed method is not capable of displaying a satisfactory treating function because of clogging of the filter medium 101 used in the immersion type aerobic filter bed 100, a lowering in the filtering function for the SS, and so on.
Therefore, it has been a common practice, as shown in FIG. 1, to provide a sedimentation basin 103 at the stage precedent to the immersion type aerobic filter bed 100 so as to preliminarily remove the SS to a predetermined level.
The sedimentation method, however, involves the problem that because of not so high an SS removal rate, it is impossible to obviate satisfactorily the clogging of the immersion type aerobic filter bed 100, together with the problems of a long treating time and a poor efficiency. In addition, the sedimentation basin 103 is large in size and requires a large installation space.